OMAP3 clock: only unlock SDRC DLL if SDRC clk < 83MHz

According to the 34xx TRM Rev. K section 11.2.4.4.11.1 "Purpose of the
DLL/CDL Module," the SDRC delay-locked-loop can be locked at any SDRC
clock frequency from 83MHz to 166MHz.  CDP code unconditionally
unlocked the DLL whenever shifting to a lower SDRC speed, but this
seems unnecessary and error-prone, as the DLL is no longer able to
compensate for process, voltage, and temperature variations.  Instead,
only unlock the DLL when the SDRC clock rate would be less than 83MHz.

Signed-off-by: Paul Walmsley <paul@pwsan.com>

2 files changed, 8 insertions, 5 deletions

diff --git a/arch/arm/plat-omap/include/mach/sram.h b/arch/arm/plat-omap/include/mach/sram.h
index ab35d622dcf5..dca7c16ae903 100644
--- a/arch/arm/plat-omap/include/mach/sram.h
+++ b/arch/arm/plat-omap/include/mach/sram.h
@@ -23,7 +23,8 @@ extern u32 omap2_set_prcm(u32 dpll_ctrl_val, u32 sdrc_rfr_val, int bypass);
 
 extern u32 omap3_configure_core_dpll(u32 sdrc_rfr_ctrl,
                                      u32 sdrc_actim_ctrla,
-                                     u32 sdrc_actim_ctrlb, u32 m2);
+                                     u32 sdrc_actim_ctrlb, u32 m2,
+                                     u32 unlock_dll);
 
 /* Do not use these */
 extern void omap1_sram_reprogram_clock(u32 ckctl, u32 dpllctl);
@@ -60,7 +61,8 @@ extern unsigned long omap243x_sram_reprogram_sdrc_sz;
 
 extern u32 omap3_sram_configure_core_dpll(u32 sdrc_rfr_ctrl,
                                           u32 sdrc_actim_ctrla,
-                                          u32 sdrc_actim_ctrlb, u32 m2);
+                                          u32 sdrc_actim_ctrlb, u32 m2,
+                                          u32 unlock_dll);
 extern unsigned long omap3_sram_configure_core_dpll_sz;
 
 #endif
diff --git a/arch/arm/plat-omap/sram.c b/arch/arm/plat-omap/sram.c
index 38353386e91e..876f5a7ecafd 100644
--- a/arch/arm/plat-omap/sram.c
+++ b/arch/arm/plat-omap/sram.c
@@ -365,16 +365,17 @@ static inline int omap243x_sram_init(void)
 static u32 (*_omap3_sram_configure_core_dpll)(u32 sdrc_rfr_ctrl,
                                               u32 sdrc_actim_ctrla,
                                               u32 sdrc_actim_ctrlb,
-                                              u32 m2);
+                                              u32 m2, u32 unlock_dll);
 u32 omap3_configure_core_dpll(u32 sdrc_rfr_ctrl, u32 sdrc_actim_ctrla,
-                              u32 sdrc_actim_ctrlb, u32 m2)
+                              u32 sdrc_actim_ctrlb, u32 m2, u32 unlock_dll)
 {
         if (!_omap3_sram_configure_core_dpll)
                 omap_sram_error();
 
         return _omap3_sram_configure_core_dpll(sdrc_rfr_ctrl,
                                                sdrc_actim_ctrla,
-                                               sdrc_actim_ctrlb, m2);
+                                               sdrc_actim_ctrlb, m2,
+                                               unlock_dll);
 }
 
 /* REVISIT: Should this be same as omap34xx_sram_init() after off-idle? */